(1) Field of the Invention
The present invention relates to a camera having a function to encode and output captured images, a camera system using the same, and an image processing circuit used in the same.
(2) Description of the Related Art
Some conventional cameras have a function to encode captured images and output the encoded images to an external network.
Such cameras are used as surveillance cameras, for example. A receiver connected to a network receives images captured by the cameras, and outputs the images to a display such that an operator can monitor the images.
Meanwhile, a capability to capture images at a high resolution and a capability to capture wide images called panoramic images are demanded of such cameras.
For example, to meet the demand for high resolution, a prior art suggests a technique to capture an image of an object with a camera equipped with a plurality of image sensors each capturing a segment of the image of the object, and synthesize the segment images.
For example, FIG. 1 illustrates the structure of a camera disclosed in Japanese Laid-open Patent Application Publication No. 9-224180 that is aimed at realizing high resolution.
The camera disclosed in this publication is equipped with imaging lenses 1001a to 1001d and CCDs 1002a to 1002d for capturing divided images of the object. The images captured by the CCDs 1002a to 1002d are respectively subjected to preprocessing (e.g. white balance and gamma correction) performed by preprocessing circuits 1003a to 1003d, and to distortion correction performed by distortion correction circuits 1004a to 1004d. A synthesizing circuit 1006 synthesizes the images respectively distortion-corrected by the distortion correction circuits 1004a to 1004d. 
With this structure, the camera is capable of synthesizing the segment images to obtain a high-resolution image.
However, if a camera is equipped with a plurality of image sensors, it is difficult to realize high resolution with flexibility and scalability.
In other words, even if a camera is equipped with four image sensors each offering one mega pixels, and is capable of capturing images of four mega pixels, it is impossible for the camera to capture images with higher resolution, such as images of 8 mega pixels and images of 10 mega pixels.
To obtain images with higher resolution, it is necessary to manufacture a camera equipped with a larger number of image sensors.
Also, if a camera is equipped with four image sensors arranged in a row each offering 0.1 mega×0.1 mega pixels to obtain panoramic images of 0.4 mega×0.1 mega pixels, the camera can capture only panoramic images, and it is impossible for the camera to obtain images of general sizes.
In terms of the problems above, the present invention aims to provide a camera system that fulfills the demand for high resolution and has high scalability.